Hydraulic transformer



Filed Sept. 20, 1965 w @v QR INVENTOR. 62 5205 fl [/VE/F April 18, 1967c. B LIVERS 3,314,367

v HYDRAULIC TRANSFORMER Filed Sept. 20, 1965 v 2 Sheets-Sheet 2 vINVENTOR. B 614E405 31/1 0519 gwi a United States Patent "ice 3,314,367HYDRAULIC TRANSFORMER Carlos B. Livers, Studio City, Calif., assignor toCrane Co., Burbank, Calif., a corporation of Illinois Filed Sept. 20,1965, Ser. No. 488,679 Claims. (Cl. 103-49) This invention relates tovariable displacement pump ing apparatus, and has as its principalobject to provide a fluid pumping device of extremely light weight suchas to adapt it especially for vehicles wherein weight-saving is of primeconsideration.

Toward the attainment of this broad object, the invention provides afluid pressure transformer apparatus which utilizes one fluid to drive aseries of axially-slidable pistons in a positive displacement pump whichdelivers another fluid to a load (such as one or more hydraulicactuators or servo motors) utilized in controlling the travel of thevehicle or other phases of operation of the environmental apparatus inwhich my hydraulic transformer may be utilized.

In a more specific application, the apparatus is adapted to utilize afluid under pressure at one level to drive a pump delivering a fluid ata different pressure level to the load.

In a particular application, the invention utilizes fuel at its normalpressure (the relatively low pressure level of the apparatus) tosequentially move a plurality of relatively large pistons of a pistonmotor, and the movements of these pistons are transmitted to acorresponding series of relatively small pistons which deliver therelatively high pressure hydraulic fluid (e.g. oil) output of thetransformer which is utilized to act upon the load. All systems of thisgeneral type involve a hydraulic motor driving a hydraulic pump. To dothis in a literal sense results in a bulky inefficient package. It istherefore important to directly couple the motor pistons to the pumppistons avoiding the conversion of energy into bearings, rotatingshafts, seals, etc. In previous proposals the art has used a rotatingvalve driven by a small separate hydraulic motor to produce thenecessary reciprocating movement of the pistons. The present inventiondiffers in that the pistons are also valves. The mechanism is automaticand continuous motion is achieved without the aid of separatemotor-driven valves. The pistons on the fuel side operate as a hydraulicmotor and the pistons on the oil side operate as a hydraulic pump. Theforces generated by the fuel pistons are transmitted directly to the oilpumping pistons. A Wobble-motion connector, tying the piston setstogether, is used to control stroke and timing but consumes no powerother than very minor bearing friction. Since the pump operates in theexact reverse of the motor, the motor will be described more in detailthan the pump.

The principal object of the invention is to provide a hydraulictransformer of maximum simplicity and minimum Weight. In the transformerof this invention, it is possible to avoid the necessity for usingconventional rotating cylinder blocks, heavy thrust bearings and shaftseals; normal problems of efliciency, Weight, size and complexity areessentially eliminated; and an extremely eflicient, simple andlightweight construction is achieved. While the invention was initiallydesigned for use as a pressure booster or intensifier, in its broadaspects it is also applicable to a pressure de-intensifier and flowbooster in which pistons of smaller diameter are acted upon by drivefluid to drive respective pistons of larger diameter which generatelower pressure and higher flow in the pump fluid than that of thedriving fluid.

The invention also-has application as a system isolator where it isdesired to transfer power from one system 3,314,367 Patented Apr. 18,1967 to another without fluid mixing. In such applications the ratio ofdisplacement is usually one to one and the unit is completely reversibleand capable of transmitting power but not fluid in either direction. Italso may be used to separate different fluids and/0r gasses.

Additional objects of the invention are to provide a hyddraulictransformer;

(l) Wherein precessive stroking operation of the pistons is controlledby a wobble-motion control coupling between pistons;

(2) Wherein very little power is consumed by this control coupling;

(3) Wherein the coupling has a number of functions, including:

(a) controlling the stroke (b) controlling valve timing (0) returningthe motor pistons on their exhaust strokes and sectioning being asindicated by line 2-2 of FIG. 1

((1) moving the pump pistons on their suction strokes.

(4) Minimizing internal leakage;

(5) Avoiding the necessity for piston-return springs or springs for anyother purpose;

(6) Avoiding the necessity for moving seals and requiring only a limitednumber of static seals;

(7) Adaptable for the use of steel for almost all of its parts;

(8) Requiring hardening only in the wear surfaces of its cylinder bores,and utilizing tough, fracture-resistant metal throughout its housingstructure;

(9) Of high degree of simplicity in the construction, arrangement andoperation of its parts;

10) A minimum of four pistons may be used in both the motor and the pumpportions and the number may be increased in any multiple of four.

Other objects and advantages will become apparent in the ensuingspecification and appended drawing in which: FIG. 1 is an axialsectional view of the transformer;

FIG. 2 is an end view, partially in section of the transformer;

FIG. 3 is a schematic piston stroking and flow diagram of the basic fourpiston unit; and

FIGS. 4 and 5 are fragmentary cross-sectional views taken on lines 4-4and 5-5 respectively.

General description In the drawings I have shown, as an example of oneform in which the invention may be embodied, a hydnaulic pressurebooster comprising, in general, a motor unit A and an axially opposedpump unit B, each comprising an annular array of cylinders and acorresponding array of pistons therein. The cylinders and pistons ofmotor unit A are of relatively large diameter, for response torelatively low fuel pressure, and the cylinders and pistons of pump unitB are of relatively small diameter, for developing relatively highpressure in the hydraulic fluid (e.g. oil) which is pumped thereby.

A wobble-motion connector C couples the pair of pistons of each set toone another, and couples the complete annular array of piston setstogether for controlling the stroking of the pistons and timing of thevalves in a precessive relation to one another such that each piston, inits stroking position, will lead the immediately following piston by apercentage of the complete stroking cycle, equivalent to the fraction ofa complete revolution represented -by the angular spacing betweenadjacent pistons, where they are equi-angularly spaced, as in thepreferred form of the invention.

The basic motor (or pump) unit of the invention requires four pistons,each piston being in the form of a spool valve. Circumferentialmanifolds appropriately its mid-stroke position is not only switchingfrom pressure to return, or the reverse as required, but it is alsomoving at its greatest speed so as to provide very napid valve action.This takes place at a time when the neighboring piston being controlledis at top or bottom dead center where its speed is virtually zero. Thisideal condition allows the valves to be made with a small but positiveoverlap thus providing highly desirable low leakage conditions. Eachpiston receives driving pressure during its full power stroke andsimilarly is connected to the return system during its retractingstroke. The number of pie tons .used may be increased in multiples offour. The invention contemplates an optimum of twelve pistons in boththe motor and the pump, all pistons having the same stroke. This resultis attained simply by pivotally connecting the pistons to the connectorC on pivot centers disposed in a common plane.

The motor cylinders are bored in an integral motor cylinder block whichis generally in the form of a cylindrical sleeve having a wall thicknesssuificient to encompass the cylinders. Each cylinder therein, tho-ughbored as a single unit, is functionally divided into two sections whichwill hereinafter be referred to respectively as a reaction cylinder 11,in which fuel will react against the forward end of a motor reactionpiston land 12, and a valve cylinder 13, in which a spool valve element(composed of a valve piston land 14, the rear end of reaction pistonland 12, and an integral connecting stem is axially slidable.correspondingly, each cylinder of the pump unit- B, formed in a pumphousing section 110, is divided into a reaction cylinder 111 in which apump reaction piston land 112 reacts against hydraulic liquid thereinwith a pumping effect, and a valve cylinder 1:13 in which a spool valveelement 112, 114,115 is axially slidable. The motor 'andpump cylindersare arranged in sets each comprising a cylinder 11, a cylinder 13, acylinder 113 and a cylinder 1 11, all aligned on a common stroking axis;aligned in sets each comprising a motor piston having lands 12 and 14and a pump piston having lands 112 and 114. The pistons further includerespective integral heads 16, 116 of zonal-spherical form integrallyjoined to respective lands 14, 114 by reduced necks 17, 117 andcorrespondingly, the pistons are axially-.

having'fiat ends abutted one against the other, in radiallyhousingjacket 18 which includes an extended portion sur-' rounding theconnector C and functioning as a crank case within which the connectoris rotated and lubricated.

Motor block 10 is provided at its outer end with a coaxial inlet fitting19 providing an inlet port for fuel. Fitting 19 is mounted in an'inletthroat 211 which is defined by the cylindrical inner wall of block 16and leads to a manifold 23 through which the fuel is distributed to therespective valve cylinders 13. Manifold 23 is formedas a deep, narrow,annular radial slot in motor block 10 intersected by the cylinders 11and the pistons 12 which pass theret-hrough. The motor block isreinforced by a cylindrical collar 21 secured in throat 20 in a positionbridging across the opening between throat 20 and manifold 23, collar 21having a plurality of ports 22. The manifold 23 functions as a commoninlet port 24 for the respective cylinders and defines a boundarybetween the valve cylinders 13 and the reaction cylinders 11,

at the outer ends' of the valve cylinders. At the inner ends of thevalve cylinders 13 is a similar annular valve outlet port 25 of deepannular slot form, communicating with a combined crank-case and outletchamber 27 which is defined withinthe crank case portion of housingjacket 18 and which in turn communicates with a motor outlet port 28defined by a lateral fitting 29 in one side of crank case jacket 18.

Extensions of valve cylinders 13 beyond the valve outlet ports 25provide integral sleeve bearings 30 in which the piston lands 14 areslidably supported.

Each of the valve cylinders 13 is provided in its outer side with atransfer port 35 communicating with one end of a respective transferpassage 36 the other end of which communicates, through a secondtransfer port 37, with an associated reaction cylinder 11circumferentially displaced from the respective valve cylinder 13. As anoptimum arrangement for solving the geometry of the apparatus, theassociated cylinders are angularly displaced apart. This makes itpossible to build a transformer with four, eight, twelve (or largermultiples of four) cylinderpiston sets. The specific arrangement shownin the drawing utilizes twelve sets, there being three independentgroups of associated sets.

It may now be noted that, for each piston-cylinder set, a valve chamber33 is defined within the respective valve cylinder 13 between therespective piston lands 12, 14 which, connected by the respective stem15, constitutes a slida'ble' spool valve element as previously stated.The chamber 38 will shift axially within the respective cylinder 13 inaccordance with the piston stroke, and at a retracted piston position(e.g. as shown at the bottom of FIG. 1) the chamber 38 will communicatewith the valve inlet port 24 while the corresponding valve outlet port25 is closed by the respective piston land 14, whereby inlet flowentering through the port 20 and passing through a respective manifoldport 22 will be directed through the respective chamber 38 and itstransfer port 35 into a transfer passage 36 which will lead the flow toa respective reaction cylinder 11, in which the fuel will react againstthe outer end of a piston land 12 to commence to drive the piston set ina power stroke. The power stroke (just completed) of the piston at thetop of FIG. 1 is indicated by arrow 41 At the same time, a diametricallyopposed piston set (e.g. the one shown at the top of FIG. 1) willcommence to move in a retracting or return stroke. The return stroke(just completed) of the piston at the bottom of FIG. 1, is indicated byarrow 41. 'Such return movement is transmitted to the pistons by theconnector C, and this will result in the discharge of fuel from thereaction cylinder" 11 of the retracting set in a return flow through itstransfer port 37, its respective transfer passage 36, and its.respective transfer port 35 into'the valve chamber 38 of an advancingpiston set which communicates with the respective valve outlet 25, thecrank case chamber 27 and the motor outlet port 28. The indicated returnflow from the cylinder in the background of FIG. 1, through the valvechamber atthe top of FIG. 1, is just completed and at the cutoff orswitching stage; These flows are indicated by the lines of arrows inFIG. 1, the full line and dotted-line arrows indicating flowsin orbehind the cross-sectional plane of this figure, and the dot'dash arrowsindicating flow in front of the plane of FIG. 1. It should be noted thatthe port 37 shown in FIG. 1 lies at the back side of the motor as viewedin FIG. 1. The transfer passage 36 leading upwardly from the lower sideof FIG. 1 is shown' in dot-dash lines to indicate the fact that thispassage lies in front of the plane of FIG. 1 and leads to a'port 37diametrically across from the port 37 as 'seenin FIG. 1.

For a more complete understanding of the precessive stroking and timingof the pistonsand valves, it may be noted at this point that the valvingaction in each valve cylinder 13 commences at a point where the pistonis at a substantial distance from the end of itsstroke, and that theswitch from pressure flow to return flow occurs when a piston is atmidst-roke and at maximum velocity. Referring now to the motor piston atthe bottom of FIG. 1, it will be seen that its valving action in thetransfer of fuel at inlet pressure through valve inlet port 24, valvechamber 38, port 35 and the transfer passage 36 extending in front ofthe plane of the drawing, began at the midpoint of the return stroke 41of the respective piston, the port 24 being rapidly opened to permit theflow to commence rapidly, and the flow continuing while the piston hasreached the end of its return stroke and has commenced a power stroke40, in response to inlet fluid which commences to enter its reactioncylinder 11 at the point where its stroke is reversed. The valvingaction of this piston, in transferring inlet fluid to the valve port 37above the plane of FIG. 1 will continue as the piston moves back tomidstroke, at which point the inlet valve port will be closed and theoutlet valve port 26 will commence to open, thus switching the flowthrough the valve chamber 38 associated with this piston. Referring nowto the port 37 and its associated reaction cylinder and piston in frontof the plane of FIG. 1 to which the incoming fuel has been directed bythe valving action just referred to, and which is disposed at 90 betweenthe two cylinder-piston sets seen in FIG. 1, it will be apparent thatthis piston at the 90 position will be at the midpoint of its strokewhen the valving piston (at the bottom of FIG. 1) has completed itsreturn stroke and commences to reverse as shown, and that the front 90piston now referred to will have been at the end of its retractingstroke and commencing its power stroke at the point where the valvingpiston at the bottom of FIG. 1 has reached its mid-position andcommenced to open its associated valve inlet port 24 and tocorrespondingly start the transfer of pressure fluid to the reactionchamber 11 of the front 90 position piston. During the half cycle ofmovement of the valving piston in which it completes the last half ofits retracting stroke and the first half of its power stroke, thepower-stroking piston will have completed its power stroke from-itsfully retracted position to its fully extended position correspondingtothat of the upper piston of FIG. 1.

At the same time, the cylinder-piston set associated with the transferport 37 indicated in the background in FIG. 1, will have been at the endof its power stroke when the piston seen at the top of FIG. 1 was at itsmidstroke position in which it commenced to open its associated valveoutlet port 25, and the rapid mid-stroke movement of this upper pistonhas quickly opened the outlet port 25 to provide for rapid escape of thefuel from the 90 background cylinder as its respective piston hascommenced its retracting stroke under push applied to it by theconnector C.

The pump B has an arrangement of transfer passages 136 functioning inthe same manner as the transfer passages 36 of the motor but arrangedinternally of the pump cylinder housing 110 instead of externally, andcommunicating with a plurality of valve inlet ports 123 and transferports 135 and 137 corresponding functionally to the ports 23, 35 and 37of the motor unit.

Each of the transfer passages 136 communicates at one end, through atransfer port 135, with a respective valve cylinder 113 and at its otherend, through a transfer port 137 with a reaction cylinder 117 angularlyoffset 90 from the respective valve cylinder 11-3.

Hydraulic oil enters the pump through an inlet port 120, travels to thevalve inlet ports 123 through a central passage defined by a throat 146,and passes through a port 123 when a pump piston is in a retractedposition as shown at the bottom of FIG. 1. Thence it passes through thetransfer port 135 into a transfer passage through which it travelsaxially and circumferentially from the valve chamber 113 through whichthe fluid is being passed. The retracting stroke of the piston in thereaction cylinder to which the fluid is thus transferred will continueuntil its cylinder 111 is filled with fluid. During continued operationa return stroke is delivered to this piston by the connector C, whichwill force the fluid out of its chamber 111 under relatively highpressure through its associated transfer port 137 in a return flowthrough an associated transfer passage 136 to a valve chamber 113 inwhich the spool valve 112, 114, 115 is in a position to direct thispressurized flow through its respective valve outlet port into adischarge manifold 118 and thence through a discharge port 128, thusproviding a discharge.

The most efiicient arrangement of the transfer passages 36 is one inwhich they extend helically side by side, sep-' arated by helicalpartitioning fins 45 which preferably are formed integrally with thecylindrical periphery of the motor housing 10. Other configurations forextending the passages 36 axially and circumferentially can be utilized,especially where a smaller number of cylinder-piston sets are employed,but the optimum configuration for a full twelve sets is helical asdisclosed.

The cylindrical jacket 18 encircles and is fitted, secured and sealed tothe peripheral surfaces of fins 45 by any suitable means, such asbrazing. The jacket 18 provides a common peripheral closure for all ofthe passages 36. At the outer end of the motor housing, the fins 45 aremerged in an end wall 47 in the form of a flat ring disposed in a planenormal to the major axis of the transformer, and the inner ends of thefins 45 are similarly merged in an offset wall 48 in the form of a ring.

Passages 136 are defined between helical fins 145 formed externally onthe cylindrical inlet throat 146 which has at its outer end the inletport 120. The peripheral surfaces of fins 145 are fitted, secured andsealed to a cylindrical inner wall of the pump cylinder housing 110, inwhich there are provided the valve ports 123, and 137. The ports 123 areof annular channel form, concentrically encircling the valve cylinders113 at the inner ends thereof. Respective valve outlet ports 125,likewise of annular channel form encircling the outer ends of valvecylinders 113, are in communication with the pump outlet manifold 11-8encircling the outer end of the pump cylinder housing 110 anddischarging through the outlet port 128.

At their outer ends, fins are merged with a fiat annular end wall 147and at their inner ends they are merged with an annular offset wall 148in the form of a fiat ring normal to the major axis of the transformer.From the periphery of offset wall 148 a cylindrical collar extends to anannular radially inwardly extending web 156 from which a bearing boss157 projects axially into the throat 146. Valve inlet ports 123 areextended through the peripheral collar 155.

The outer ends of reaction cylinders 11 and 111 are closed by annularcap rings 60, 160 and are sealed by O-rings 61, 161 compressed betweenthe cap rings 60, 160, the walls of cylinders 11, 111 and the heads ofthreaded studs 62, 162 which extend through apertures in the cap rings60, 160 and are drawn tight by nuts 63, 163.

The projecting portion of motor-crank case jacket 18 terminates in aninwardly offset neck 65 which is fitted around a flanged end portion 66of the pump cylinder block 110 and sealed thereto by an O-ring 67disposed in an annular groove in the end portion 66.

While the construction and operation of the motor and the pump have beendescribed in full detail herein for a full understanding of theconstruction and operation of the complete apparatus, the pump per se issimilar in construction and operation to the fluid motor of my priorPatent No. 2,994,306, issued Aug. 1, 1961, which discloses such a motorwith its pistons in driving engagement with a wobble-plate which drivesa crank shaft from which rotary power is delivered. Also, is may benoted that an arrangement wherein free-floating pistons of a motor arepaired with aligned floating pistons of a pump for driving the same, isdisclosed in the prior application of Jorge Alfredo Morando, Ser. No.286,620, filed June 10, 1963 for Hydraulic Transformer, wherein thepistons are spring-loaded for return movement, and

wherein a separate motor driven rotary valve is provided for timing andcontrolling the operation of the pistons. The present invention is animprovement over the hydraulic transformer of that application in thatthe necessity for the rotary timing valve and its separate driving motorhas been eliminated, and in that a Wobbleplate is utilized, not fortransmiting power, bu only as a means for retaining the pistons incoupled relation and for transmitting return strokes thereto (when thepistons are not under load). The wobble-plate mechanism will now bedescribed.

Connector C comprises a Wobble-plate 70 having a hub 71 journalledthrough anti-friction bearings 72 upon respective ends of a skewed crankshaft 73, so that the latter may rotate to accommodate nutatingmovements of the wobble plate. Crankshaft 73 has respective crank throws74, 75 with integral trunnions 76, 77. Trunion 76 is journalled in abearing 78 within a boss 79 on a central partition wall 80 which closesthe inner end of motor inlet throat 20 and against which the manifold 21(a narrow cylindrical ring) is seated. Trunnion 77 is journalled in abearing 81 which in turn is mounted within the bearing boss 157 of thepump inlet throat 146. The boss 157 and annular Web 156 cooperativelyclose the inner end of the pump inlet throat 146.

Wobble-plate 70 has an integral rim 85 of channel section, interruptedby radial slots 86 in its periphery, the piston stems 1'7, 117 beingsnugly embraced in these slots so as to provide coupling connectionsbetween the wobbleplate 70 and the pistons, in which there is nosubstantial circumferential play. Bearing pads 87 are embraced betweenthe walls of rim channel 85, the pads being of ring form, withzonal-spherical bearing recesses in which the correspondingly sphericalsurfaces of piston head 16, '116 are seated for universally pivotalmovement. The pads 87 are slidable radially against the inner .walls ofthe rim channel 85 as the connector C nutates, thus accommodatinglimited radial and circumferential shifting movements of the pads andpivotal movements of the piston heads to accommodate'tliewobble-movement of the connector C.

Reviewing the operation of the apparatus, as fluid onder pressure isdelivered into the inlet throat 20' of the motor A, the pistons thereofwill execute power strokes as hereinbefore described, in precessiveorder as illustrated in FIG. 3, and will transmit corresponding powerstrokes directly to the pistons of pump B through the abuttingengagement of piston heads 16, 116 within the embrace of connector C.Movement is simultaneously transmitted to the connector C forcontrolling the timing and stroking of the pistons in the properprecessive order through the valving operation of the pistons, and fortransmitting the return movements to the pistons, but since neither thevalving movements nor the return strokes of the pistons are opposed byany load, and none of the load transmitted from the motor to the pumpthrough the abutting pistons is carried by the, connector C, only anegligibly small portion of the transmitted power is utilized ineifecting nutation of the wobble-plate 70 and the valving and returnmovements of the pistons. The loading of its bearings by the rotatingcrank shaft 'will likewise be negligible. Thus the invention avoids theconversion of any appreciable amount of energy into bearings, rotatingshafts, seals etc. Since each piston in passing through its mid-strokeposition is not only switching from pressure to return, or the reverseas required, but is also moving at its greatest speed, very rapid valve:action takes place at a time when the neighboring piston beingcontrolled therebyis at top or bottom dead center where its speed isvirtually zero, and is highly efiicient.

The term fluid as used herein is intended to embrace both liquids andgases.

I claim:

1. A hydraulic transformer comprising a motor unit Operable y 0. 15 flud and an axially-opposedpump unit for pumping another fluid, said unitsincluding means defining respective annular arrays of reaction cylindersand valve cylinders; and respective piston sets each including pistonsslidable in the respective reaction cylinders and spool valve elementslidable in the respective valve cylinders to provide respectiveflow-control valves; inlet and outlet ports connected to the respectivevalve chambers in axially-spaced relation; transfer passages eachconnecting a respective valve cylinder to a respectivecircumferentially-displaced reaction cylinder; and control meanscoupling said piston sets for precessive stroking of said pistons suchthat said valves will operate to connect said transfer passagesalternately to said inlet and outlet ports so as to switch from intaketo return flow precessively in said reaction cylinders; said annulararrays of cylinders being arranged with each reaction cylinder alignedwith a respective valve cylinder and with the cylinders of one arrayaligned with the cylinders of the other array; said pistons beingarranged in opposed, aligned pairs, each pair having abutting ends inthe form of heads with universally pivotal bearing surfaces, and havingreduced necks connecting said heads -to their respective pistons; saidcontrol means comprising a nutating wobble-plate having peripheralsocket means, and bearing pads confined in said socket means inuniversallypivotal, embracing bearing engagement with the abutting headsof respective piston pairs so as to tie the sets of pistons together totransmit return strokes to the valve pistons, with the heads of therespective pairs in pressure-transmitting relation so as to directlytransmit pressure from one piston of a pair to the other along thecommon longitudinal axis of the pair of pistons.

2. A hydraulic transformer comprising axially-opposed motor and pumpunits including respective housing means having respective annulararrays of motor reaction cylinders, pump cylinders and correspondingvalve cylinders, said cylinders being arranged in sets each comprising amotor cylinder, a pump cylinder and a respective valve cylinder alignedon a common axis, each valve cylinder having respective valve inlet andoutlet ports; a set of aligned pistons axially slidable in each set ofcylinders and comprising a motor reaction piston in' a respective motorcylinder, a pump piston in a respective pump cylinder, spool valve landsin the respective valve cylinders, and respective stems each connectinga respective motor reaction piston to a respective valve land andconstituting therewith a respective slide valve spool which is slidablein a respective. valve cylinder to provide a respective control valve;each of said pump and 'motor units having means defining a plurality oftransfer ports each connecting a respective reaction cylinder to arespective valve cylinder circu'mferentially displaced therefrom; and awobble-movement connector linked to said piston sets and constrainingthem to maintain a timed stroke relationship such that said controlvalves will operate to connect said transfer passages alternately to therespective inlet and outlet ports so as to switch from intake to returnflow precessively in said reaction cylinders. V

3. A hydraulic transformer comprising a motor unit operable by a fluidatone pressure and an axially-opposed pump unit for pumping a fluid atanother pressure, said units including means defining respective annulararrays of reaction cylinders of different diameters and valve cylindersaligned with the respective reaction cylinders, the cylinders of onearray being aligned with those of the other; and respective piston setseach including pistons slidable in the respective reaction cylinders,spool valve elements slidable in the respective valve cylinders toprovide respective flow-control valves, and reduced diameter stemsintegrally connecting the spool valve elements to the respective pistonsin alignment therewith, inlet and outlet ports connected to therespective valve chambers in axially-spaced relation; transfer passageseach connecting' a respective valve" cylinder to a respective circumferentially-disposed reaction cylinder; and control means comprisinga wobble-plate having universallypivotal connections with the inner endsof respective pistons, coupling said piston sets to one another'so as totransmit both pumping strokes and return strokes to the pistons of thepump unit in response to power strokes of the pistons of said motor, andoperative to control precessive stroking of said pistons such that saidvalves will operae to connect said transfer passages alternately to saidinlet and outlet ports so as to switch from intake to return flowprecessively in said reaction cylinders.

4. A hydraulic transformer comprising axially-opposed motor and pumpunits including respective housing means having respective annulararrays of motor reaction cylinders, pump reaction cylinders andcorresponding valve cylinders, said cylinders being arranged in setseach comprising a motor cylinder, a pump cylinder and a respective valvecylinder aligned on a common axis, each valve cylinder having respectivevalve inlet and outlet ports; a set of aligned pistons axially slidablein each set of cylinders and comprising a motor reaction piston in arespective motor cylinder, a pump piston in a respective pump cylinder,spool valve lands in the respective valve cylinders, and respectivestems each connecting a respective piston to a respective valve land andconstituting therewith a respective slide valve spool; each of said pumpand motor units having means defining a plurality of transfer ports eachconnecting a reaction cylinder to a valve cylinder; and aWobble-movement connector linked to said piston sets and constrainingthem to maintain a timed stroke relationship such that said valve spoolsWill operate to connect said transfer passages alternately to therespective inlet and outlet ports so as to direct incoming fluid throughthe valve of one set to the reaction cylinder of another set of the samecircumferential array while directing exhaust flow from the reactioncylinder of one set through the valve of another set and thence to therespective outlet port.

5. A hydraulic transformer as defined in claim 3, wherein the motor unitcylinders and pistons are aligned with respective pump unit cylindersand pistons, wherein aligned valve pistons have opposed ends in directabutting, pressure transmitting engagement, and wherein said abuttingends are coupled to said connector so as to maintain said abuttingengagement at all times, and so that return strokes of the pump pistonswill be transmitted to them through said connector.

References Cited by the Examiner UNITED STATES PATENTS 2,293,076 8/1942Ponting 103-49 2,356,917 8/1944 Chouings 10349 2,592,940 4/1952 Monoyer103-51 ROBERT M. WALKER, Primary Examiner.

1. A HYDRAULIC TRANSFORMER COMPRISING A MOTOR UNIT OPERABLE BY ONE FLUIDAND AN AXIALLY-OPPOSED PUMP UNIT FOR PUMPING ANOTHER FLUID, SAID UNITSINCLUDING MEANS DEFINING RESPECTIVE ANNULAR ARRAYS OF REACTION CYLINDERSAND VALVE CYLINDERS; AND RESPECTIVE PISTON SETS EACH INCLUDING PISTONSSLIDABLE IN THE RESPECTIVE REACTION CYLINDERS AND SPOOL VALVE ELEMENTSLIDABLE IN THE RESPECTIVE VALVE CYLINDERS TO PROVIDE RESPECTIVEFLOW-CONTROL VALVES; INLET AND OUTLET PORTS CONNECTED TO THE RESPECTIVEVALVE CHAMBERS IN AXIALLY-SPACED RELATION; TRANSFER PASSAGES EACHCONNECTING A RESPECTIVE VALVE CYLINDER TO A RESPECTIVECIRCUMFERENTIALLY-DISPLACED REACTION CYLINDER; AND CONTROL MEANSCOUPLING SAID PISTON SETS FOR PRECESSIVE STROKING OF SAID PISTONS SUCHTHAT SAID VALVES WILL OPERATE TO CONNECT SAID TRANSFER PASSAGESALTERNATELY TO SAID INLET AND OUTLET PORTS SO AS TO SWITCH FROM INTAKETO RETURN FLOW PRECESSIVELY IN SAID REACTION CYLINDERS; SAID ANNULARARRAYS OF CYLINDERS BEING ARRANGED WITH EACH REACTION CYLINDER ALIGNEDWITH A RESPECTIVE VALVE CYLINDER AND WITH THE CYLINDERS OF ONE ARRAYALIGNED WITH THE CYLINDERS OF THE OTHER ARRAY; SAID PISTONS BEINGARRANGED IN OPPOSED, ALIGNED PAIRS, EACH PAIR HAVING ABUTTING ENDS INTHE FORM OF HEADS WITH UNIVERSALLY PIVOTAL BEARING SURFACES, AND HAVINGREDUCED NECKS CONNECTING SAID HEADS TO THEIR RESPECTIVE PISTONS; SAIDCONTROL MEANS COMPRISING A NUTATING WOBBLE-PLATE HAVING PERIPHERALSOCKET MEANS, AND BEARING PADS CONFINED IN SAID SOCKET MEANS INUNIVERSALLYPIVOTAL, EMBRACING BEARING ENGAGEMENT WITH THE ABUTTING HEADSOF RESPECTIVE PISTON PAIRS SO AS TO TIE THE SETS OF PISTONS TOGETHER TOTRANSMIT RETURN STROKES TO THE VALVE PISTONS, WITH THE HEADS OF THERESPECTIVE PAIRS IN PRESSURE-TRANSMITTING RELATION SO AS TO DIRECTLYTRANSMIT PRESSURE FORM ONE PISTON OF A PAIR TO THE OTHER ALONG THECOMMON LONGITUDINAL AXIS OF THE PAIR OF PISTONS.